What is the diff between vitamin D1 and D3 & the vitamin D that has to be bought with prescription?

I have found differences in the units, but what I really mean is the differences in the chemistry & the indications. I know vit D helps preserve the Calcium in bones, but what other indications are for the diff types of vit D?

Answers (1)

German researcher Adolf Windaus first discovered 3 forms of vitamin D, which he called D1, D2, and D3. It was later learned that the vitamin D1 was a mixture of compounds rather than a pure vitamin D product, so the term D1 is no longer used.

The term "Vitamin D" now refers to several different forms.The two forms important in humans are : ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Vitamin D2 is a synthetic form (man made) and Vitamin D3 is the internal form that we make.

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